Ball shear strength of 63Sn-37Pb solder bump with test conditions

摘要

The 63Sn-37Pb solder balls were reflowed on different URMs (Au/Ni/Cu, Ni/Cu and Cu), and ball shear strength of the solder bumps was characterized with variations of reflow time, shear tip position, shear speed, and solder bump shape. The shear strength of the 635n-37Pb solder bumps did not change with varying the reflow time at 22O□, and was not dependent on the thickness of intermetallic compounds. Regardless of the dwell time at the reflow temperature, the solder bump reflowed on Cu UBM exhibited higher shear strength than that reflowed on Au/Ni/Cu UBM When the relative shear tip position was less than h'2 where h was the bump height, shear strength was independent upon the relative shear tip position. On the contrary, shear strength decreased with increasing the shear tip position when it was larger than W2. With increasing the shear speed, shear strength increased due to the strain rate hardening of 635n-3 7Pb solder. The slopes of the curve for shear strength vs. shear speed were the same without depending on the sizes of the solder ball and UBM which could be attributed to the fact that strain rate hardening is a material constant and does not depend on the shape factor of a specimen. Shear strength of the 63Sn-3 7Pb bumps varied with the sizes of solder ball and UBM due to the effective crack size change.